If you are near an Apple store, take it to them. Most of them are very generous in helping users out with their issues; many times even when out of warranty. This will likely be your most efficient method in getting things straightened out.
You haven't given nearly enough information for specific ideas on what to do first. Is the iPad working when not plugged in to the computer? If not, what happens? Can you update your iPad via WiFi or 3G? There are many helpful websites that give you multiple ways of restoring your iPad, but unless we know exactly what is happening and what your end result should be, the best I can do is point you to:
https://www.google.com/search?q=restore+ipad+to+factory
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